The present invention relates to a steering system for an endless track type tractor, and more particularly, to a hydraulic control system of the steering system for the endless track type tractor having dual power trains.
Heretofore, a steering system for an endless track type tractor having dual power trains has been developed in which the transmissions and the steering brakes are hydraulically actuated selectively through the hydraulic cylinders and the electromagnetic valves coupled thereto and controlled by a switch mechansism by the hydraulic fluid pressure supplied from a hydraulic fluid source so as to turn the tractor rightwardly or leftwardly. In such a steering system as described above, since the electromagnetic valves are actuated instantaneously to either one of the two positions the hydraulic fluid of the contstant pressure is instantaneously supplied to the hydraulic cylinders so that the rate of the turning of the tractor, i.e., the radius of curvature of the turning of the tractor is made constant thereby deteriorating the operation of the tractor.
The present invention aims at avoiding the disadvantages of the prior art steering system for an endless track type tractor described above.